Question

A parabola is represented by the equation y2 = 5x. Which equation represents the directrix? 
y = –20x = –20y = -5/4x = -5/4

Answer 1

Answer:

On ed its x = -5/4

Step-by-step explanation:

Answer 2

Answer:

$x=-\frac{5}{4}$

Step-by-step explanation:

Given equation,

$y^2=5x-----(1)$

Which is the equation of a parabola along x-axis,

From equation (1),

$(y-0)^2=\frac{4}{4}\times 5(x-0)$

$(y-0)^2=4(\frac{5}{4})(x-0)-----(2)$

We know that, the standard form of a parabola along x-axis is,

$(y-k)^2=4p(x-h)$

Where, the directrix is,

x = h-p

By comparing equation (2),

The directrix of the given parabola is,

$x = 0 - \frac{5}{4}\implies x = -\frac{5}{4}$